make OUTPUT subdirs

Simplifies compute programs.

Remote/Compute.hs

@@ -476,6 +476,11 @@ runComputeProgram (ComputeProgram program) state (ImmutableState immutablestate)
 			liftIO $ hPutStrLn (stdinHandle p) $
 				toCommand' (File f)
 			liftIO $ hFlush (stdinHandle p)
+			-- If the output file is in a subdirectory, make
+			-- the directories so the compute program doesn't
+			-- need to.
+			liftIO $ createDirectoryIfMissing True $ 
+				takeDirectory (subdir </> f')
 			knownoutput <- case M.lookup f' (computeOutputs $ computeState result) of
 				Nothing -> return False
 				Just mk -> do

doc/design/compute_special_remote_interface.mdwn

@@ -110,6 +110,5 @@ An example `git-annex-compute-foo` shell script follows:
     echo REPRODUCIBLE
 
     if [ -n "$input" ]; then
-        mkdir -p "$(dirname "$output")"
         frobnicate --passes="$ANNEX_COMPUTE_passes" <"$input" >"$output"
     fi

doc/special_remotes/compute/git-annex-compute-imageconvert

@@ -17,6 +17,5 @@ echo "OUTPUT $2"
 read output
 
 if [ -n "$input" ]; then
-	mkdir -p "$(dirname "$output")"
 	convert "$input" "$output"
 fi